Mechanical Anisotropy and Pressure Induced Structural Changes in Piroxicam Crystals Probed by In Situ Indentation and Raman Spectroscopy

The ability to correlate mechanical and chemical characterization techniques in real time is both lacking and powerful tool for gaining insights into material behavior. This is demonstrated through use of a novel nanoindentation device equipped with Raman spectroscopy to explore the deformation-induced structural changes in piroxicam crystals. Mechanical anisotropy was observed in two major faces (\( 0\bar{1}1 \)) and (011), which are correlated to changes in the interlayer interaction from in situ Raman spectra recorded during indentation. The results of this study demonstrate the considerable potential of an in situ Raman nanoindentation instrument for studying a variety of topics, including stress-induced phase transformation mechanisms, mechanochemistry, and solid state reactivity under mechanical forces that occur in molecular and pharmaceutical solids.     

Prediction of Evaporation Losses in Wet Cooling Towers

The accurate prediction of all aspects of cooling tower behavior is very important. Accurately predicting evaporation losses is significant because water in cooling towers is cooled primarily through the evaporation of a portion of the circulating water, which causes the concentration of dissolved solids and other impurities to increase. An empirical relation is developed on the basis of ASHRAE's rule of thumb that is simple and accurate with a wide range of applicability. The predicted values are in good agreement with experimental data as well as predictions made by an accurate mathematical model.     

Thermoeconomic considerations in the design and rating of two-phase heat exchangers

We discuss a closed-form model for thermoeconomic design and analysis of two-phase heat exchangers used as condensers and evaporators. The results are presented in terms of the optimum number of heat-transfer units (NTUs) as a function of the dimensionless unit-cost ratio and the exit-to-inlet absolute temperature ratio of the single-phase fluid. The sensitivities of various unit-cost parameters (UCPs) are presented. It is demonstrated that the selection of UCPs play a significant role in sizing heat exchangers.     

Correction to: Similar Feed-forward Loop Crosstalk Patterns may Impact Robust Information Transport Across E. coli and S. Cerevisiae Transcriptional Networks

Mobile Networks and Applications - The original version of this article unfortunately contained a mistake in the author group section. Author Preetam Ghosh’s given name was incorrectly...     

Comparison of Conventional and Cross-Layer Multimedia Transport Schemes for Wireless Networks

Three competing schemes have been proposed for multimedia transport over broadband wireless channels: (a) traditional UDP (Postel, The User Datagram Protocol, 1980 [1]), (b) semi-cross-layer UDP-Lite (The Lightweight User Datagram Protocol, 2004 [2]), and (c) cross-layer header estimation (Khayam et al., IEEE Transactions on Multimedia 9(2):377–385, 2007 [3]; Khayam and Radha, IEEE Transactions on Wireless Communications 6(11):3946–3954, 2007 [4]). In all these schemes, corrupted and lost packets are recovered using FEC at the application layer. In this paper, we analytically and experimentally compare the performances of these broadband wireless multimedia schemes. First, we derive lower bounds on the excepted FEC redundancy required by ideal cross-layer header estimation, UDP and UDP-Lite over an arbitrary-order Markov wireless channel. We show that under realistic wireless channel conditions, the cross-layer header estimation scheme always requires lesser redundancy than UDP and UDP-Lite. We then propose a practical minimum distance decoding (MDD) header estimation scheme, which is receiver-based, low complexity and highly accurate. Trace-driven multimedia experiments over wireless LANs demonstrate that MDD header estimation requires significantly lesser FEC redundancy and renders better video quality than existing schemes.     

A Functional Programming Framework for Latency Insensitive Protocol Validation

Latency insensitive protocols (LIPs) have been proposed as a viable means to connect synchronous IP blocks via long interconnects in a system-on-chip. The reason why one needs to implement LIPs on long interconnects stems from the fact that with increasing clock frequencies, the signal delay on some interconnects exceeds the clock period. Correctness of a system composed of synchronous blocks communicating via LIPs is established by showing latency equivalence between a completely synchronous composition of the blocks, and the LIP based composition. A design flow based on a synchronous composition specification, and stepwise refinement to LIP composition can be easily conceived, and a proof obligation to show latency equivalence between the synchronous specification and the refinement needs to be discharged. In this work, we propose a functional programming based framework for modeling and simulating LIP, and implement the semantics of various refinement steps in the programming model, so we can validate the LIP model against the original system within this functional programming framework. Such validation becomes easier due to the inherent denotational model of functional languages. We specifically use Standard ML to model the original system implementation as well as its latency insensitive version and compare the two by creating a model that contains both, giving them the same inputs and checking their outputs to be latency equivalent.